How this calculator works
- Step 1Your value1.5 TRIn any of five units.
- Step 2To watts5,275.28 WWith a NIST conversion factor.
- Step 3Every unit18,000 Btu/hBtu/h, W, kW, TR and kcal/h.
BTU per hour, watts and tons of refrigeration all measure power: how fast heat is moved or produced. Air conditioners are sold in India by tons and rated in watts, while many other markets quote BTU per hour.
A British thermal unit is the heat that warms a pound of water by one degree Fahrenheit. A ton of refrigeration is defined as 12,000 BTU per hour, roughly the cooling of a ton of ice melting over a day.
Worked example: a 1.5-ton air conditioner
- Btu/h
tons × 12,000- Watts
tons × 3,516.853
- 1.5 × 12,00018,000 Btu/h
- 1.5 × 3,516.853 W5,275.28 W
- In kilowatts5.28 kW
Common sizes
Reading a label
- A 5.2 kW rating17,743 Btu/hAbout 1.48 tons.
- A 2,000 W heater6,824 Btu/hAll of its electricity becomes heat.
Cooling capacity is not power drawn: a 1.5-ton AC moves about 5.3 kW of heat while using much less electricity, which is what its efficiency rating measures.
Related energy tools
BTU per hour, watts and tons all measure power. Running cost depends on hours of use.
To estimate what an air conditioner adds to your bill, use the electricity calculator. For other unit conversions, the unit converter covers length, mass, volume, temperature and speed.
Common mistakes
Mistake: Reading BTU as BTU per hour.
Instead: AC capacity is a rate, BTU per hour; a BTU alone is an amount of energy.
Mistake: Treating the cooling rating as electricity use.
Instead: Check the rated input power and the efficiency figure on the label.
Methodology and sources
A separate script derives every factor from the joule value of a BTU and the 12,000 Btu/h ton, and checks NIST’s published ton factor.
The conversion factors come from NIST Special Publication 811, Appendix B.9. Sources and the review date follow.
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